Narrative: The curved blade for harvesting crops with long stalks such as grains has been in use for millenia. Examples have been found using flints set in curved bone - dating to the very beginning of agriculture!
So universal was the use of the curved sickle in pre-mechanized farming that it was adopted (along with the hammer) as an iconic symbol in the Russian Revolution in 1917.
A bundle of stalks of the desired crop is held in one hand, or the crook of an arm, while the sickle blade is drawn across them, effecting the cut.

Description: A hand-held tool used for cutting tall grass or stocks of grain with a curved, hook-like blade mounted in a short light wooden handle.